US 1461028 A
Description (OCR text may contain errors)
July 3Q, 1923.
L. K. DAVIS ENDLES S TRACK VEHICLE Filed March 20 1925 2 Shams-Sheet 1 July E0, 1923.
1 4611 6328 L. K. DAVIS ENDLESS TRACK VEHICLE Filed March 20, 1923 2 Sheets-Sheet 2 mmwl Lewis 1712mm STTS Patented duly lid, l
DAVI5, 015 WASHINGTON, ElllQTEIECT OF GOJL'UMBLA,
ll LESS-TRACK VEHICLE.
Application filed March 20, 1928. Serial 1110. 626,378.
To all whom it may concern:
Be it known that l, Luwrs K. DAvIs, a citizen of the United States, residing in the city of Washington District of Columbia, have invented certain new and useful Improvements in Endless-Track Vehicles, or which the following is a specification.
This invention relates" to vehicles of the class in which endless tracks or tractor belts are employed to sustain the vehicle and traverse the ground, and especially to'that class of such vehicles in which the track islald down in front of bogies or other supporting devices which bear on the lower runs of the belts.
Various methods of steering such vehicles havebeen suggested, but none have been entirely satisfactory owing to the fact that usually in steering, those portions of the track which bear on the ground are moved sidewise and skid or-scrape the ground and often considerable strain is thus placed on the mechanism. Such vehicles when provided with steering wheels at the front and tractor belts at the rear may be steered 1n the usual way and it has heretofore been sugted to steer such vehicles by bending the belts laterally and also to brake one of the driving pulleys and by difierential gearing to increase the speed of the other driving pulley. in such last mentioned cases,
however, serious strains have been placed on the mechanism, which it is the object of my invention-to avoid.
According to my invention, the endless tracks are made laterally flexible, prefer ably by means of a universal jomt between each pair of linlrs composing the track. The driving pulleys andthe idlers for the belts are suitably supported in the vehlcle frame, while the weight of the vehicle is earned by bogies or body supporting members which bear on the lower runs of the belts and am yieldingly connected with the veincle body. These body supporting members are so connected and so mounted as to allow the tracks to bend or flex laterally while still engaging the supporting members and they are preferably so mounted that they can move not only vertically but also laterally or horizontally to follow the lateral movements of the tracks when the latter are moved laterally and especially when so moved during the steering o ration. The driving pulleys are er with suitable brakes and these p *vertically or about horizontal axes.
able form of belt is shown in Figure 6 com eye are connected with brake.
each other by difierential gearing of the kind in which when the brake is applied to one of the pulleys to reduce its speed, the
speed of the other pulley is corres ondingly or proportionally increased. ere are many kinds of such gearing'in the prior art which may be employed and which are suitable for my pus. v By my invention a tractor may be efficiently steered by merely applying the brake to one of the driving pulleys and by reason of the laterally flexible tracks the laterally movable body supporting members employed and the difierential gearing used, the vehicle may be readily turned or steered without undue strain on the mechanism.
In the accompanying drawings:
Figure 1 is a plan view ofso much of an endless track vehicle with my improvements applied as is necessary to illustrate the invention herein claimed.
Figure 2 is a side elevation thereof.
Figure 3 is a plan view similar to Figure 1 but showing how the tracks are warped or bent laterally when the vehicle is being steered.
Figure 4 shows a transverse section of the vehicle.
Figure 5 is a sectional view showing details of a bogie or body supporting member.
Figure 6 is a plan view of a form of tree tor belt or track which may be employed.
The frame or chassis is indicated at A and may be of any suitable kind. The endless belts or tracks B may be of any desired construction so long as they can be bent laterally or about vertical axes as well A suitprising links or shoes 6 connected by universal or ball joints h.
The tracks traverse idle pulleys C mounted in beari in the chassis and driving pulleys D applied to miles 0?, cl, the inner ends of which are connected to ditlerential gearing within the housing E.
I have not shown-the details of the differential gearing employed as there are many kinds that may be used. ll preferably,
however employ controlled differential gearing of the hind shown, described and claimed in the application tor shout out George John Rackham, filed ugust '1 1922, N0. 57s on.
Each the l, a is provided with a suitable Preferably brake d ll and llllll are employed associatedwith brake bands f, g, operated bytightenlng devices it actuated by Wires or cables H extending to steerin mechanism L.
he pulleys C, D are raised above the ground level and the weight of theyehrcle 15 carried by bogies or body supporting members M which bear on the lower runs of the belts or tracks. These body supporting members may take various forms, but they should be so mounted as to be adapted to move laterally with the belts during the steering operaton. Preferably, each body supporting member comprises a pair of wheels N mounted in a frame 0 through which extends a horizontally arranged rod P that'connects a body supporting member on one side of the vehicle with a body supporting member on the opposite side thereof. These frames 0 are free to slide inde endently on the rods P to a limited extent. ach rod P carries posts p which extend into sockets a in downwardly projecting frame members R and springs S are interposed between the members R and the clamps 7* which attach the posts to the rods.
The rollers or wheels N extend into grooves b in the track shoes and the construction is such that when the tracks are moved laterally the wheels N with their frames 0 will also move laterally. It will the opposite side of the vehicle.
therefore be seen that the body supporting devices or bogies are moved laterally by the belts and with the belts whenever the belts are given lateral movement for steering purposes or for any other reason.
, By means of the or anization shown the vehicle may be steere by merely applying the brake to one of the driving pulleys, causing it to slow down and at the same time through the controlled diflerential gearing employed, to speed up the driving pulley on The degree of increase may be adjusted to any deslred extent by employing properly formed gearing members. i
By reference to Figure 3 it will be seen that if the brake is applied to the brake drum F and loosened on the brake drum G the speed of the driving pulley on the axle D will be reduced and the speed of the pulley on the axle d will be increased, thus causin the tractor belt connected with the axle d to increase its speed, thus causing the vehicle to turn in the manner indicated by full lines, the normal or straight ahead position of the parts being indicated by dotted lines. Full lines in Figure 3 show the relative positions of the parts in actual service while steering.
' I clalm as my invention:
1. An endless track vehicle comprising a frame, endless flexible tracks carried thereby, a frame supporting member bearing on the lower run of each track and each mounted to move laterally in unison with a corresponding lateral movement of the portion of the track which it engages, driving pulleys and idlers for the tracks, differential earing connecting the driving pulleys an independently operable brakes therefor, the application of either brake reducing the speed of the associated pulley and correspondingly increasing the speed of the other pulleyv to bend laterally only the lower reach of said track between the pulleyand idler and give lateral movement to the body supporting members.
2. An endless track vehicle comprising a frame, driving pulle s and idlers mounted thereon, endless traclts associated with the pulleys, differential gearing connecting the driving pulleys, a brake for each drivin pulley, independent means for applying and withdrawing each of the brakes, and body supporting members which bear on the lower runs of the tracks and transmit the weight of the vehicle thereto, which are mounted to move laterally or transversely of the vehicle with the laterally movable'tracks, whereby steering is performed solely by application of brake to one pulley, therebyredu'cing its speed and increasing the speed of the other pulley to bend the tracks laterally and give lateral movement to the body support- 1ng members.
3. An endless track vehicle comprising a frame, driving pulleys and idlers mounted thereon, endless tracks or tractor belts associated with the pulleys and comprising a series of shoes connected by joints permitting the tracks to bend vertically and laterally, difl'erential gearing connecting the driving pulleys, a brake for each driving pulley, independent means for applying and withdrawing each of the brakes and bogies which bear on the lower runs of the belts and transmit the weight of the vehicle thereto, which are mounted to move laterally or transversely of the vehicle with the laterally mov-' ing belts, the steering being performed solely by application of the brake to one of the driving pulleys to bend laterally only the lower reach of the track and lay it down in a curve.
4:. An endless track vehicle comprising a vehicle body, laterally flexible tracks associated therewith, differential gearing for drying the tracks, means for controlling the gearing to drive one track faster than the other, said means alone operating to bend the tracks .and steer the vehicle, and body supporting rollers engaging the tracks and mounted for lateral movement on the vehicle body, which allow the tracks to bend laterally while still engaging the rollers.
5. An endless track vehiclepomprising a vehicle body, driving pulleys and idle pulleys associated therewith, dfferential gearing for actuating the driving ulleys, means for controlling the gearing to drive the track the vehicle body which allow the tracks to on one side of the vehicle faster or slower bend laterally while still engaging the rollthan the other, said means alone operating ers.
to bend the tracks and steer the vehicle, In testimony whereof, I have hereunto 10 5 and body supporting rollers engaging the subscribed my name.
tracks and mounted for lateral movement on LEWIS K. DAVIS.